On 16 January, the US Navy announced – via a posting on the federal government's procurement website – that the F-35’s joint programme office intends to award multiple contracts to Lockheed Martin to develop Block 4 software, with the first contract expected to be awarded in October 2014.

The contracts will include “assessments and evaluations” to ensure Block 4-equipped aircraft meet “future operational requirements”, it says.

When completed, Block 4 software will provide the F-35 with improved radar and electronic warfare systems, and allow the aircraft to carry additional weapons used by both the US military and other F-35 customers.

A document posted on the website of the US Embassy in Norway – a customer for the conventional take-off and landing F-35A – provides more details, however.

This states that aircraft with the Block 4 software package will be able to carry joint stand-off cruise missiles – including Kongsberg's Joint Strike Missile – all variants of small-diameter bombs and Raytheon AIM-9X Sidewinder Block II air-to-air missiles.

Additionally, the iterative development will add an automated ground collision avoidance system, better protection from hacking and improvements to power and thermal management, to avoid issues that have been raised over the JSF's integrated power package since at least 2007. These culminated in a grounding of the F-35 fleet in 2011.

Block 4 upgrades will also give F-35s the ability to carry speed-reducing drag chutes deployed at landing, which will allow the aircraft to land on icy runways – a critical capability for F-35 partners like Norway.

It will also have streaming video from its electro-optical targeting system and an improved ability to identify targets, the document states.

The contracts are likely to call for development of a prototype to test systems, upgrades to hardware, engineering and design work and for the acquisition of technical, administrative and financial data, the navy's notice says.

The F-35 programme office says Lockheed is likely to build prototypes of subsystems and components, but not a dedicated Block 4 test aircraft.

The Block 4 software has only received funding in the 2014 fiscal year. The US Department of Defense will spend $6 million on the project in this fiscal period, including $1.5 million from the USN, $3 million from the US Air Force and $1.5 million from the US Marine Corps, the programme office says.